The catalytic behaviour of glassy carbon electrode modified by 1.2-dihydroxy anthraquinone (Alizarin) was investigated. The electrocatalytic ability of modified electrode for the reduction of dioxygen was examined by cyclic voltammetry and Rotating disk electrode (RDE) voltammetry techniques. The Alizarin modified glassy carbon electrode possesses excellent electrocatalytic abilities for dioxygen reduction over potential 400 mV lower than at the bare glassy carbon electrode. Hydrodynamic studies were performed to determine the heterogeneous rate constants for the reduction of O2 at the surface of modified electrode was determined by Koutecky–Levich plot. The apparent diffusion coefficient of O2in O2 saturated acidic medium solutions was estimated by using Levich equation. Studies show the involvement of four electrons in dioxygen reduction at the surface of this modified electrode.
